1. Field of the Invention
The present invention relates to a lens system suitable for film camera, a television camera, a video camera or the like for performing image blur correction caused by vibration or fluctuation due to the hand vibration or wind by using an optical image blur correction optical system such as a shift lens (an image blur correction lens moving in a vertical direction to an image taking optical shaft) that is moved in a direction perpendicular to an optical axis of an image taking optical system or a variable apex angle prism (variable angle prism, VAP) or the like and a camera system composed of a camera provided with the lens system.
2. Related Background Art
In a conventional zoom lens having fluctuation preventing function, an optical image blur correction optical system is controlled so as to correct the vibration or fluctuation such as hand vibration detected by a fluctuation detection means so that the control of the image blur on the image forming plane is performed. In such a fluctuation preventing zoom lens, since the fluctuation or vibration such as hand vibration detected by the fluctuation detection means is corrected irrespective of the intention of the operator, and, the correction is effected for the vibration generated when the lens is moved in the horizontal direction or in the vertical direction, i.e., in so-called panning or tilting so that the operator determines the frame for the image pickup. There is a problem on the image taking operation when the frame is determined by the operator. Therefore, there has been an approach to effect the correction by judging the vibration generated when the operator performs the panning or tilting and the vibration such as hand vibration or the like generated irrespective of the operator""s intention. For example, in Japanese Patent Application Laid-open No. 4-86735 (Japanese Patent Application No. 2-201183: U.S. Pat. No. 5,229,603), in an angular shift meter for detecting an angular shift of vibration generated in the camera, the vibration detection characteristics, particularly, the vibration detection frequency band of the angular shift meter are changed in accordance with the angular shift output of the angular shift meter. Namely, the vibration amplitude (angular shift) falls within a predetermined range in case of the normal hand vibration, whereas there is a large angular shift in the operation such as panning, and the judgement as whether the vibration is caused by the intentional operation or not is performed in accordance with the magnitude of the generated angular shift, thereby obtaining the optimum vibration detection characteristics of the sensor, i.e., image blur correction characteristics in accordance therewith.
However, a zoom lens has a focal length converting optical system that is detachable and called an extender separated from the zoom optical system and an angle of view on the image may be largely changed by attachment or detachment of the extender. Namely, in the case where the extender having the conversion magnification ratio of k times is inserted, the view angle after the insertion is 1/k of the view angle before the insertion. In such a case, when the panning is or the like is effected, since the ratio of the vibration, generated by the panning or the like, to the view angle is changed to k times by the insertion of the extender, the movement of the image field could not follow the intention of the cameraman, and there is a problem in that he or she feels something different.
An object of the present invention is to provide a lens system that may suppress a strange feeling to the cameraman generated due to the difference in conversion ratio of a focal length converting optical system in panning and/or tilting and to provide a camera system provided with the lens system.
In order to attain this and other objects, according to the present invention, there is provided a lens system comprising:
an image taking optical unit having an optical axis;
a correction optical component for tilting the optical axis of the image taking optical unit;
a conversion optical component insertable into or retractable from the optical axis of the image taking optical unit;
a vibration sensor for detecting a vibration;
a insertion or retraction detection sensor for detecting whether the conversion optical component is disposed on the optical axis of the image taking optical unit or not;
a driver for driving the correction optical component to tilt the optical axis of the image taking optical unit; and
a controller for controlling the drive of the correction optical component by the driver in response to the detection output from the vibration sensor, characterized in that:
when the detection output from the vibration sensor exceeds a predetermined limit value, the controller controls the drive of the driver so that the correction optical component is located in the vicinity of the optical axis; and
the controller changes the limit value in correspondence with the output from the insertion or retraction detection sensor.
Also, according to the present invention, there is provided a lens system comprising:
an image taking optical unit having an optical axis;
a correction optical component for tilting the optical axis of the image taking optical unit;
a shift sensor for detecting a shift amount of the correction optical component;
a conversion optical component insertable into or retractable from the optical axis of the image taking optical unit;
a vibration sensor for detecting a vibration;
a insertion or retraction detection sensor for detecting whether the conversion optical component is disposed on the optical axis of the image taking optical unit or not;
a driver for driving the correction optical component to tilt the optical axis of the image taking optical unit; and
a controller for controlling the drive of the correction optical component by the driver in response to the detection output from the vibration sensor, characterized in that:
when the detection output from the shift sensor exceeds a predetermined limit value of the shift amount, the controller controls the drive of the driver so that the correction optical component is located in the vicinity of the optical axis; and
the controller changes the limit value in correspondence with the output from the insertion or retraction detection sensor.
Note that other structures and objects of the present invention will be apparent in th e description of the following embodiments.